Defense Secretary Chuck Hagel, right, is greeted by Air Force Maj. Gen. Sandra E. Finan, commander of the Air Force Nuclear Weapons Center on Kirtland Air Force Base, N.M., as he arrives to visit Sandia National Laboratories in Albuquerque on Jan. 8. (Glenn Fawcett/Defense Department)

KIRTLAND AIR FORCE BASE, NEW MEXICO — Defense Secretary Chuck Hagel said he’s worried about morale among the Air Force missileers who work in isolation manning nuclear weapons silos and launch pads.

“It is lonely work,” Hagel told reporters here Wednesday. “I think they do feel under appreciated many times. They are stuck out in the areas where not a lot of attention is paid and I know they wonder more than occasionally if anyone is paying attention.”

Hagel’s comments came during a two-day trip visiting several nuclear weapons facilities and the troops who operate them. The trip comes at a time of mounting criticism of the Air Force’s management of nuclear weapons and concern about morale in some units.

For years missileers have hoped for some form of incentive pay, similar to those granted to pilots and troops with special language skills. But Hagel said he’s not looking at that right now.

“I think it’s not so much a pay and compensation issue. I just think it’s these young, smart people are wondering if what I’m doing with my life, is it important? Does it make a difference? Am I appreciated? Do people really care?”

Hagel spoke to reporters at Kirtland Air Force Base after touring a nuclear weapons vault, visiting Sandia National Laboratories and meeting with commanders of the 898th Munitions Squadron, which operates an underground depot-level weapons maintenance and storage facility. The squadron helps develops the military’s policies and practices for handling nuclear weapons worldwide.

On Thursday, Hagel will visit F.E. Warren Air Force Base in Wyoming, home to about 150 Minutemen III intercontinental ballistic missiles. He will tour a missile launch site and hold a town hall-style meeting with personnel.

“I think that psychic reinforcement, to any of us, is really important and that is a responsibility that our leaders have, starting with me. ... One of my intentions is to acknowledge that when I’m there tomorrow. To thank them and tell them how important their work is.”

Hagel said he’ll talk with airmen and commanders “focusing on not just morale but the purpose of what they are doing and why they are doing it and acknowledging that what they’re doing is important.”

In addition to boosting morale, Hagel is also checking up on the Air Force’s management of the ICMBs after a string of mishaps and embarrassments.

In October, the Air Force fired Maj. Gen. Michael Carey, commander of 20th Air Force, which is responsible for the Air Force’s entire arsenal of Minuteman III intercontinental ballistic missiles. Air Force officials said Carey drank too much and behaved inappropriately during a recent trip to Russia.

Gen. Mark Welsh, Air Force chief of staff, told reporters in November that the service must “add more vigor” to its screening of candidates for senior nuclear commands.

Welsh also recently approved a revamped inspection regimen for nuclear commands. Col. Richard Coe, commander of the Air Force Inspection Agency, said Wednesday that the new rules will instill “a culture of rigorous self-assessment.”

In October, the Associated Press revealed that four ICBM launch officers were disciplined earlier in 2013 for napping while the blast door to their underground command post was left open, posing risks that an intruder could tamper with equipment or compromise secret launch codes.

Thousands of airman are assigned to the isolated installations that maintain ICBMs — Malmstrom Air Force Base in Montana, F.E. Warren Air Force Base in Wyoming and Minot Air Force Base in North Dakota. They man the silos and launch sites 24 hours a day waiting for an order from the president that has never come.

Since the end of the cold war, the ICBMs and the nuclear deterrence they are intended to provide has become a far lower priority for the Pentagon.

Some officials in Washington are talking about reducing the size of the launch-ready ICBM force. A defense bill that became law in July authorizes the Defense Department to study the potential closure of some missile silos and reduce the ICBM force below 450 in accordance with a new treaty with Russia. Some lawmakers oppose those closures.

Concerns about the management of nuclear capabilities also comes at a time when the Pentagon is facing a massive round of modernizations because many of the current weapons are old and will need replacement during the next 10 to 20 years. The Pentagon’s acquisitions chief, Frank Kendall, is also traveling with Hagel on his tour of nuclear facilities this week.

The Congressional Budget Office recently projected the cost of maintaining the ICMB arsenal at about $20 billion for the next ten years, and the Pentagon will likely spend close to $190 billion to upgrade the weapons and maintain their communications systems.